I have a technical question about rockbox on the xduoo x3...
Did a comparison between various DAPs with RMAA.
Devices that have 16 bit DACs have a noise floor of about -130dB.
Devices that have 24 bit DACs have a noise floor of about -140dB.
The xDuoo X3 scored -107dB SNR and a -140dB noise floor using rockbox playing a 24bit 44.1KHz rmaa test file.
The question is, if rockbox doesn't support hi-res, why is the noise floor -140dB instead of -130dB and why is the SNR -107dB instead of -96dB which is the maximum theoretical limit for 16 bits?
You can peak at this video for a visual description of the above
https://youtu.be/KXM9VVtphJg?t=2769
I suspect that rockbox actually supports 24 bits 48KHz on this player.